Malnutrition is a state in which a deficiency of nutrients such as energy, protein, vitamins and minerals causes measurable adverse effects on body composition, function or clinical outcome. In this guideline we do not use the term to cover excess nutrient provision.

Malnutrition is both a cause and a consequence of ill health. It is common and increases a patient's vulnerability to disease. Methods to improve or maintain nutritional intake are known as nutrition support. These include:

  • oral nutrition support – for example, fortified food, additional snacks and/or sip feeds

  • enteral tube feeding – the delivery of a nutritionally complete feed directly into the gut via a tube

  • parenteral nutrition – the delivery of nutrition intravenously.

These methods can improve outcomes, but decisions on the most effective and safe methods are complex.

Currently, knowledge of the causes, effects and treatment of malnutrition among healthcare professionals in the UK is poor. This guideline aims to help healthcare professionals correctly identify people in hospital and the community who need nutrition support, and enable them to choose and deliver the most appropriate nutrition support at the most appropriate time.

The recommendations in this guideline were graded according to the quality of the evidence they were based on. The gradings are available in the NICE guideline and are not shown in this web version.